At long last, iTunes 5 brings variable bit rate (VBR) encodi...

[MacBytes]

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Category: News and Press Releases
Link: At long last, iTunes 5 brings variable bit rate (VBR) encoding of AAC tracks (http://www.macbytes.com/link.php?sid=20050908165504)

Posted on MacBytes.com (http://www.macbytes.com)
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[ham_man]

I may have to reimport all my music at VBR 192. Beats LAME with a stick...;)

[Loge]

The article was unclear about what VBR at a specified bit rate really means. Is it an average bit rate so the file size is similar but quality should be higher due to the more efficient encoding or something else? I'd like to know more before reripping stuff.

[telecomm]

The article was unclear about what VBR at a specified bit rate really means. Is it an average bit rate so the file size is similar but quality should be higher due to the more efficient encoding or something else? I'd like to know more before reripping stuff.

While I'm not absolutely certain, it's probably safe to assume that VBR AAC works like VBR MP3 files in iTunes—the bit rate selected is the lowest rate at which audio will be encoded, so at 128, for example, the bit rate will never be worse than 128.

Here's an old link. (http://docs.info.apple.com/article.html?artnum=60794)

[dubbz]

Some quick testing done by some people in another forum I visit suggest that Apple still have some work to do.

VBR is about choosing a quality level that the encoder should target, using whatever (within limits) amount of bits that is neccessary. Right now, it's closer to ABR (the encoder try to maintain a average bitrate, but will use a few more bits if required).

Still, it's an improvement, however small it might be.


(And this is of course all very early testing. To be taken with a grain of salt).

[fpnc]

While it is true that this is new to iTunes it has been possible to encode in AAC VBR ever since QuickTime 7 was introduced. Thus a few months ago I used the QuickTime Pro Player to encoded a few songs in AAC VBR to test on my iPod shuffle and 3G iPod, it worked without any problems.

[combatcolin]

I take it that this mode works in the same way as MPEG 2, where busier scenes take up more space then quieter sections.